COSMOD Power

[Edge540]

Hello,
Yet another smoke detector question...
Id just like to verify my wiring method is acceptable or is the common method and I'm just over thinking it...

I will have a COSMOD2W Module with 6ea 2WTA-B and 3 COSMO-2W detectors attached.
Power will be from an Altronix AL400ULPD4. In order to reset the detectors, the Elk's SAUX needs to remove power from COSMOD.
I was thinking of using the SAUX's power to energize an Elk-912 relay and put the 912 inbetween the AL400 and the COSMO instead of
shutting down the entire AL400 so other outputs of the AL400 can be used for motions and water sensors.
The 912 relay would be mounted inside the AL400 box and COSMOS external but adjacent.
Ive searched, but not finding a specific answer.
Thank you!

 

[Sandpiper]

I was concerned about whether the relay must be listed for the purpose, but could not find any such requirement. Technically it should work.
I assume you are aware of the requirement for power consumption calculations to prove you have 24 hours of backup battery power- for the smokes fed from the Altronix unit and for the alarm system. If you are going to have motions and water sensors using power, they need to be included in the calculation.

 

[Edge540]

Hello,
I have used the Elk's current draw spreadsheet with worst case amperage draws and with the motion, water, and smokes all on the AL400, the Elk-1280 battery satisfies a 4hr standby, which, i believe, all the alarms can be sounding for 4hrs.
Using standby amperages only, the Elk-12180 would satisfy a 24hr standby.
Only these sensors would be on the AL400. The M1 would be by itself and its own battery, which i understand should die before a battery powering sensors/smokes.

 

[Sandpiper]

Just so you know. Here is an excerpt from NFPA 72, concerning household fire alarm systems (what you are proposing), and their required battery backups. You have two battery backups, one for the alarm system and one for the Altronix unit. When you put install a smoke detector system into the alarm system, it becomes a household fire alarm system; no longer just a burglar alarm system. It is common practice to require 4 hour backup for burglar alarm systems , but the requirement for a household fire alarm system is 24 hours.

 

[Sandpiper]

By the way, I have a "household fire alarm system", using an ELK M1, just as you are proposing. I was able to satisfy the backup battery requirement for the alarm system by installing two parallel 7AH batteries inside the M1 cabinet. Mine has been trouble-free for quite a few years.